The preset invention relates to an apparatus for levitating objects, an apparatus for transporting objects, and an apparatus for loading objects, and more particularly, to an apparatus for levitating objects, an apparatus for transporting objects, and an apparatus for loading objects for holding an object in a levitated state using a radiation pressure such as a sound wave, transporting an object, a portion of which is in a levitated state, and transferring an object in a levitated state.
Apparatus for levitating objects of this type are disclosed, for example, in Japanese Laid-Open Patent Publications Nos. Hei 7-24415, 9-169427, and the like. As shown in FIG. 11, these apparatuses use an elongated flat diaphragm 75, and an object 76 to be levitated has a flat surface facing the surface of the diaphragm 75. Then, the diaphragm 75 is excited by an exciting mechanism 77 to levitate the object 76 by a radiation pressure of a sound wave generated by vibrations of the diaphragm 75. A horn 78 forming part of the exciting mechanism 77 is coupled to a center portion of the diaphragm 75. The aforementioned publications also disclose that the object 76 is transported in a levitated state by injecting air to the levitated object or by generating a traveling wave by the diaphragm 75 to move the levitated object 76.
When an apparatus for levitating objects is installed on a carrier car for transporting an object in a levitated state to a predetermined position, or when an object is transported to a predetermined position by an apparatus for transporting objects which transports the object in a levitated state, an operation for transferring the object at the predetermined position, i.e., a apparatus for loading objects is required. Japanese Laid-Open Patent Publication No. 2001-97531 discloses a apparatus for loading objects for loading an object in a levitated state, as shown in FIGS. 12(a) and 12(b).
As shown in FIGS. 12(a) and 12(b), a apparatus for loading objects 81 comprises a fork 82 which has a pair of fork pieces that reciprocate linearly. FIG. 12(a) is a schematic back view showing that the apparatus for loading objects is moving to a loading position, and FIG. 12(b) is a schematic back view showing the apparatus for loading objects after the completion of a loading operation. In FIGS. 12(a) and 12(b), each fork piece is arranged to extend perpendicularly to the back surface of the sheet, so that it does not appear on the figure. The fork 82 is arranged for reciprocating linearly in a direction perpendicular to the sheet of FIGS. 12(a) and 12(b) by known driving means (not shown) and is made vertically movable.
Each fork piece is provided with a plurality of apparatus for levitating objects 83. The apparatus for levitating objects 83 has a diaphragm 84 fixed to the fork piece through a horn 85, a transducer 86 and a supporting bracket 87. The apparatus for levitating objects 83 performs an operation for receiving from the apparatus for levitating objects 90 a plate-shaped object 91 held in a levitated state by an apparatus for levitating objects 90 equipped on a truck (not shown) as it remains in the levitated state.
However, in the structure which couples the elongated diaphragm 75 to the horn 78 at the center thereof for vibration as shown in FIG. 11, a deflection caused by the self weight of the diaphragm 75 is problematic. For example, the deflection due to the self weight causes the diaphragm 75 to lose flatness relative to a virtual horizontal plane, and a clearance between a levitated object 76 and the diaphragm 75 to vary. With the employment of a structure which couples the diaphragm 75 to the horn 78 forming part of the vibrating means at a plurality of locations without coupling the diaphragm 75 to the horn 78 at the center thereof, at least two transducers are required, while the adverse influence of the deflection due to the self weight of the diaphragm can be avoided, resulting in a higher cost.
In the apparatus for loading objects 81 illustrated in FIGS. 12(a) and 12(b), a plurality of diaphragms 84 are attached to each fork piece, thereby reducing the adverse influence of a deflection due to the self weight of the diaphragms 84. However, the diaphragms 84 excited by a transducer 86 must be disposed below an object held in a levitated state by another apparatus for levitating objects 90 during a loading operation, so that the apparatus for loading objects 81, with a large distance to the top surfaces of the diaphragms 84, must be introduced from a lower end of the transducer 86. As a result, a large space must be ensured, for example, for permitting the apparatus for loading objects 81 to advance into the apparatus for levitating objects 90. Another problem arises in that the apparatus for loading objects 81 itself is reduced in thickness with difficulties.
It is a first object of the present invention to provide an apparatus for levitating objects which is capable of vibrating an elongated diaphragm only with a single transducer in a stable state in a simple structure.
It is a second object of the present invention to provide an apparatus for transporting objects for transporting an object, a portion of which is in a levitated state using the above apparatus for levitating objects, in a simple structure.
It is a third object of the present invention to provide a apparatus for loading objects which requires a smaller space for moving a loading unit when an object is transferred in a levitated state.
To achieve the above objects, one aspect of the present invention provides an apparatus for levitating objects. The apparatus for levitating objects has an elongated diaphragm, a horn, a supporting member and a transducer. The diaphragm has a first end portion and a second end portion. The horn is fixed to the first end portion. The supporting member is fixed to the second end portion. The transducer is connected only to the horn. A sound wave is generated in the diaphragm and the transducer vibrates the diaphragm via the horn so that an object is levitated above a surface of the diaphragm by radiation pressure of the generated sound wave.
Another aspect of the present invention provides an apparatus for transporting objects. The apparatus for transporting objects has a transporting mechanism and an apparatus for levitating objects. The transporting mechanism transports an object in a predetermined transporting direction. The transporting mechanism supports the object with two ends of the object in a direction perpendicular to the transporting direction. The apparatus for levitating objects applies levitating force between the two ends of the object supported by the transporting mechanism to prevent deflection of an object. The apparatus for levitating objects has an elongated diaphragm, a horn, a supporting member and a transducer. The diaphragm has a first end portion and a second end portion. The horn is fixed to the first end portion. The supporting member is fixed to the second end portion. The transducer is connected only to the horn. A sound wave is generated in the diaphragm and the transducer vibrates the diaphragm via the horn so that an object is levitated above a surface of the diaphragm by radiation pressure of the generated sound wave.
Another aspect of the present invention provides an apparatus for loading objects. The apparatus for loading objects has a supporting portion, a movement mechanism, a diaphragm, a horn, a supporting member, a transducer and a driving device. The supporting portion is capable of reciprocating. The supporting portion has a base end portion and a distal end portion. The movement mechanism reciprocates the supporting portion. The diaphragm has a first end portion and a second end portion. The horn fixes the first end portion to the base end portion of the supporting portion. The supporting member fixes the second end portion to the distal end portion of the supporting portion. The transducer is connected to the horn. The driving device vibrates the transducer. A sound wave is generated in the diaphragm and the transducer vibrates the diaphragm via the horn so that an object is levitated above a surface of the diaphragm by radiation pressure of the generated sound wave.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings.